Are l3kernel and l3packages present in most of the LaTeX distributions? Are they "stable enough"?
I am asking this because I am preparing a .tex document for a client. I have found convenient to use ...

The situation is one where I'm developing my own commands and environments which build on the commands and environments provided by another package: for ease of talking let's call this other package ...

I'm trying to create an environment which uses xparse style arguments but I have to be able to use the whole environment content in the environment definition, e.g. as an argument.
Ideally I'd like ...

I would like to define a command that will behave according to the nature of the last character fed it. But I'm having difficulty just getting the components of my command to work.
I thought I could ...

I would like to define a macro for optimization problems. My attempt is given below. I am wondering why \optimizationproblema works, but \optimizationproblemb does not (I get a "misplaced alignment ...

Would it be possible to use the s argument specifier of xparse in \NewDocumentEnvironment so that we get an environment an a starred version of it?
Actually it works, but the star goes to the wrong ...

To implement a macro that takes one or more optional arguments that do not have to be placed in the first position, xargs can be used as well as xparse. The latter seems to have more recent updates ...

I'm trying to learn how to do macros.
I want to use xparse as it seems the most powerful tool.
I also want named arguments, as numbered arguments make me, as a programmer, uncomfortable.
I had some ...

I need to create a macro to render lists with a variable number of arguments (1+), e.g.
\mylist{1,2,3} should expand to $\tilde{1}$--$\tilde{2}$--$\tilde{3}$. I'm trying to use xparse and \SplitList, ...

I'm trying to redefine an existing environment subfigure defined by the subcaption package. To do this, I'm using xparse's DeclareDocumentEnvironment since that's suppose to declare a new environment ...

These days, I’m more and more defining robust commands, e.g., using \newrobustcmd (etoolbox package) or \NewDocumentCommand (xparse package). Robust commands seem advantageous to me in many respects ...

I know that I can suppress all those annoying xparse logging messages about redefining commands using the log-declarations=false package option.
I find that I can do this after xparse has been loaded ...

I have a scenario where xparse's \NewDocumentCommand has a regression compared to any alternative I know, including ones defining robust commands. So I'm avoiding \NewDocumentCommand in this case, but ...

I am trying to define a command that changes the color of every letter in the whole document to a specified color.
I already tried different approaches from this thread, but I was not able to color ...

edit: changed the MWE to show the problem with french babel
So, I was wondering about in TeX.sx and came upon this question
How do magic \dots work in amsmath?,
I wanted to do the same thing (have a ...

I am writing a text which references a whole bunch of Brazilian norms. All of these norms are prefixed with "NBR". I therefore created the following command
\newcommand*{\NBR}[1]{NBR #1\cite{NBR#1}}
...